Action return value too long for commandline

[Stuart Bishop]

On 4 April 2016 at 02:00, Merlijn Sebrechts <merlijn.sebrechts at gmail.com> wrote:
> Hi all
>
>
> The apache-kafka charm has an action "read-topic" that can return a lot of
> data. Sometimes, this data is too long to be passed to `action-set` by
> commandline. You get the following error:
>
> Traceback (most recent call last):
>   File "actions/read-topic", line 36, in <module>
>     hookenv.action_set({'output': output})
>   File
> "/usr/local/lib/python2.7/dist-packages/charmhelpers/core/hookenv.py", line
> 615, in action_set
>     subprocess.check_call(cmd)
>   File "/usr/lib/python2.7/subprocess.py", line 535, in check_call
>     retcode = call(*popenargs, **kwargs)
>   File "/usr/lib/python2.7/subprocess.py", line 522, in call
>     return Popen(*popenargs, **kwargs).wait()
>   File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
>     errread, errwrite)
>   File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
>     raise child_exception
> OSError: [Errno 7] Argument list too long
>
>
> Is there any way to pass a file to action-set?

This bug affects many of the Juju tools causing charms to fail at
scale. https://bugs.launchpad.net/juju-core/+bug/1437366
(relation-set) is the only one I know of that has been fixed.
https://bugs.launchpad.net/juju-core/+bug/1274460 (juju-log) is still
open. leader-set also fails now I think of it, but I haven't tripped
over that one (it limits scalability the way I'm using leadershp
settings, but I should be able to squeeze out several hundred units).
Maybe we can use the opportunity to fix quoting and encoding issues.

I suspect if you can get past command line length limitations, I
suspect the next glass ceiling is a 16MB document size limit in
MongoDB (which is large enough to not need fixing?)

-- 
Stuart Bishop <stuart.bishop at canonical.com>